Hi,
Michal Vaško <[email protected]> wrote:
> Hello,
>
> I would like to get some input for a use-case I came across, which to
> me does not seem to have any consistent rules that can be applied.
>
> module mod_b {
> namespace "x:example:mod_b";
> prefix "mb";
>
> grouping mylist_wrapper {
> list mylist {
> key "name";
> unique "value";
> leaf name {
> type string;
> }
> leaf value {
> type uint32;
> }
> }
> }
>
> list mylist2 {
> key "a";
> leaf a {
> type string;
> }
> leaf b {
> type string;
> }
> }
> }
>
>
> module mod_a {
> namespace "x:example:mod_a";
> prefix "ma";
>
> import mod_b { prefix "mb"; }
>
> container root {
> uses mb:mylist_wrapper;
> }
>
> augment /mb:mylist2 {
> leaf c {
> type string;
> }
> }
>
> deviation /mb:mylist2 {
> deviate add {
> unique "mb:b c";
> }
> }
> }
>
> The focus is on the "unique" statements and how to resolve
> non-prefixed identifiers. RFC 7950 says that the argument is a "list
> of schema node identifiers"[1], which use "current module" for
> non-prefixed identifiers[2]. I have asked on this mailing list a few
> years back what current module means and the answer I got was the
> module where the statement is defined.
>
> So let's get to the examples. As they are written, the unique in
> "mylist" should be wrong because the node "value" belongs to the
> module "mod_a" when the grouping is instantiated there, but unique is
> defined in the module "mod_b".
>
> But even if we use the other understanding of current module and
> interpret is as the module of the context node of the statement
> (corresponds to the "current()" XPath function), then the other
> "unique" in the deviation cannot be resolved. It is referencing node
> "c", which belongs to the module "mod_a" (added by an augment) but the
> current module would then be "mod_b".
>
> To summarize, if strictly following the specs, the "unique" in the
> "mylist" should probably reference "value" with a prefix, but that is
> not possible because "mod_a" is not even imported and it generally
> does not make sense. But then I cannot think of any consistent rule to
> successfully resolve both "unique" statements in this example. Can
> anyone help me with this, please?
Compare with this:
grouping mylist_wrapper {
list mylist {
key "name";
unique "value";
must "value > 42";
leaf name {
type string;
}
leaf value {
type uint32;
}
}
}
I think the rules for the prefixes in "unique" should be the same as
for "must". So I think that the correct syntax is to not use any
prefix in "unique".
And the deviation that adds a unique statement look correct.
/martin
> Finally, I am asking because I am trying to implement this correctly
> in yanglint. I have also tried to test these examples with pyang,
> which, however, seems to not have any consistent rules applied because
> it loads these examples without warnings. No warnings are printed even
> if the "unique" in the deviation is changed to "b c", which is
> definitely wrong since node "b" belongs to "mod_b" and node "c"
> belongs to "mod_a".
>
> Thanks,
> Michal
>
> [1] https://datatracker.ietf.org/doc/html/rfc7950#section-7.8.3
> [2] https://datatracker.ietf.org/doc/html/rfc7950#section-6.5
>
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